1. Technical Field
The present disclosure relates to a technique for calculating a camera parameter set during self-calibration of a stereo camera.
2. Description of the Related Art
In order for a user and a system to make a determination or to perform control in a driving safety support system for vehicles, a remote operation system for movable robots, a surveillance camera system used for detection of suspicious people, etc., images of the surroundings of the system and information of three-dimensional coordinates are needed.
Various techniques for acquiring, from images captured by a stereo camera, three-dimensional coordinates of a subject by using camera parameter sets of individual cameras on the basis of stereoscopy are known (see, for example, Japanese Unexamined Patent Application Publication No. 2001-285692 (PTL 1), Japanese Unexamined Patent Application Publication No. 6-167564 (PTL 2), and Japanese Unexamined Patent Application Publication No. 2007-24647 (PTL 3), Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-528304 (PTL 4), and Roger Y. Tsai, “A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV cameras and lenses”, IEEE Journal of Robotics and Automation, Vol. 3, pp. 323-344, 1987 (NPL 1)). Calculating a camera parameter set is called camera calibration. PTL 4 and NPL 1 contain a detailed description of camera calibration.
Calibration techniques of the related art, however, have an issue in that calibration is not correctly performed in the case where three-dimensional coordinates of a calibration target change due to a factor, such as aging or an external force.